Program Director/Principal Investigator (Last, First, Middle): MARTIN, ASHLEY, ANNE ABSTRACT Obesity in the USA has reached epidemic levels and is considered a disease by the CDC. The genetic contribution to the escalating obesity rate is relatively minor, implicating other causative factors, such as environment and epigenetics. Increased childhood/adolescent obesity and metabolic disturbances are linked to maternal obesity and ~1/2 of all pregnant women are overweight/obese in the USA. Thus, maternal obesity may create an ?adverse intrauterine environment? that preprograms the fetus for later obesity, following the Barker hypothesis. The main objective of this study is to determine if maternal obesity impacts development of hypothalamic neuroendocrine appetite systems that could predispose an individual to hyperphagia, increasing susceptibility to obesity. A baboon model of pre-pregnancy maternal obesity will be utilized to perform this study. Leptin is a key regulator of appetite, acting on its receptor (LEPR) in specific hypothalamic nuclei that govern food intake. LEPR desensitization can occur in the early stages of obesity due to sustained increases in plasma leptin from expanding adipose tissue, leading to appetite dysregulation. Leptin also plays a key role in neonatal rodent hypothalamic development. Maternal obesity contributes to increased fetal adiposity and hyper-leptinemia in humans. Fetuses from obese baboon mothers? trend toward an increase in serum leptin. The overarching hypothesis is that fetuses from obese pregnancy will have 1) increased serum leptin with decreased LEPR expression/signaling in the arcuate nucleus of the hypothalamus (ARH), either via desensitization /downregulation from excess leptin, 2) decreased ?MSH axonal fibers to ARH target nuclei in the hypothalamus and 3) preferential anorexigenic neuropeptide promoter methylation with decreased anorexigenic peptide expression in neuronal populations relative to orexigenic neuropeptides and neurons. Timed pregnant control (<19kg) and obese (>19kg) dams will gestate to 90% gestation (165 days gestation; term~181 days), at which time fetuses will be removed via C-section. The hypothalamus will be dissected and separated at the midline. One-half will be fixed in paraformaldehyde for immunohistochemistry (IHC) and the other half immediately frozen for isolation of the hypothalamic arcuate nucleus (ARH) for subsequent Oxidative BiSilfite Amplicon Sequencing (oxBSAS) and quantitative real-time PCR (qRT-PCR). ELISA will be used to determine fetal and maternal plasma levels of leptin. IHC will be used to determine neuropeptide and leptin receptor expression in the ARH, define projections and neuronal density throughout the appetitive neurocircuit and visualize histone modifications in the ARH. oxBSAS will be used to determine promoter-specific methylation and hydroxy-methylation of appetitive neuropeptides. qRT-PCR will be used to quantify hypothalamic ARH neuropeptide and leptin receptor expression. This study will have translational implications to human pregnancies where the fetus is subject to maternal obesity and future studies will examine means to prevent or reverse the effects of increased leptin and/or epigenetic imprints of maternal obesity. OMB No. 0925-0001/0002 (Rev. 03/16 Approved Through 10/31/2018) Page Continuation Format Page